Gecko adhesion technology moves closer to industrial uses

While human-made devices inspired by gecko feet have emerged in recent years, enabling their wearers to slowly scale a glass wall, the possible applications of gecko-adhesion technology go far beyond Spiderman-esque antics.

A Georgia Institute of Technology researcher is considering how the technology could be applied in a high-precision industrial setting, such as in robot arms used in manufacturing computer chips.

Michael Varenberg, assistant professor in Georgia Tech’s School of Mechanical Engineering, said: “There are numerous ways that gecko adhesion could be used in an industrial setting, especially in handling delicate materials like the silicon wafers used in manufacturing computer processors.”

But before robot arms and other devices can implement gecko adhesion technology, researchers need more information about the mechanical and physical characteristics of the human-made adhesive surfaces.

In his study, prof Varenberg looked at a particular type of gecko-inspired adhesive surface and narrowed down a range of angles at which the material will attach stronger and release its grip easier.

The gecko gets its unique ability using tiny hairs that interact with surfaces at an intermolecular level. It’s a one-two process during which the tiny film-like hairs are pressed onto the surface and engaged with a shearing action. They then either hold to the surface or easily release when pulled away at different directions.

For that process to be replicated in a factory using man-made adhesive technology, researchers must determine the precise angles at which to apply a load to get or release the grip between the robotic arm and the silicon wafer.

Prof Varenberg’s team tested a wall-shaped microstructure surface moulded from polyvinylsiloxane and designed to mimic the gecko's attachment ability. Their tests showed that the optimum attachment angle varies between 60 and 90°, while the microstructure detach at zero force when the pull-off angle reaches 140 and 160°.

“That relatively wide range to control the attachment and pulling away for these wall-shaped microstructures will make it easier to build a mechanical process around that tolerance,” prof Varenberg said.

That could hold promise for replacing a current method used during the processing and inspection of silicon wafers in computer processor production. Robot arms employ ceramic chucks that use vacuum or electrostatic grippers to pick up and handle the wafers. Soon after installation, the ceramic contact posts start wearing down due to cyclic loading and release particles that can potentially contaminate the backside of the wafer leading to lithography defects on its front side.

“This reality is inconsistent with the cleanliness standards required in the semiconductor industry,” Varenberg explained. “Using gecko adhesion microstructures instead would be better because they do not generate any damage to wafers and do not wear over time.”

Next, the researchers will look to simplify the manufacturing technique, working with industrial-grade materials as well as studying the effects of environment and surface geometry parameters.